Telephone-exchange



(No Model.) 3 Sheets-Sheef'1.

M. F. HILL.

TELEPHONE EXCHANGE; I No. 572,801. Patented Dec. 8, 1896.

m: NORRIS PETERS no. PHUTULI'TNOO WASHZNGTON, n I;

(No Model.) a sneets-sneetr M. P. HILL.

TELEPHONE EXGHANGB.

Patented Dec. 8, 1896.

3 sheets sheet (No Model.)

M. P. HILL. TELEPHONE EXCHANGE.

o. 572,801. Patented 1m. 8, 1896.

D" 0 I N E N WITNESSES:

UNITED STATES PATENT OFF E.

MYRON FRANCIS HILL, OF CAMBRIDGE, MASSACHUSETTS.

TELEPHONE-EXCHANGE.

SPECIFICATION forming part of Letters Patent No. 572,801, dated December 8, 1896.

Application filed July 16,1895. Serial No. 556,118. (No model.)

To all whom it may concern:

Be it known that I, MYRoN FRANCIS HILL, a citizen of the United States, residing at Cam'- bridge, county of Middlesex, and State of Massachusetts,have invented certain new and useful Improvements in Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, in which the same letters and numerals of reference refer to like parts in. the different views.

My invention has for its object to reduce the great expense of manually-operated switchboard-exchanges, to reduce the complication. of them, and to increase the speed of connections and disconnections in order to enable a smaller number of operators to take care of the work of a larger number of subscribers.

In accomplishing this result my invention permits a division of labor in accordance with the well-known tendencies in factories by which one set of operators answers a calling subscriber and another set of operators calls the called subscriber. The first set of operators I designate as answering operators and the other set as distributing operators. The answering operators are distributed among answering-boards, forming one division of boards, and the distributing operators are placed at different sections on the distributing-board. Thus there. are two divisions of boards, an answering division and a distributing division. Each division of boards is divided up into sections, each section for one or two operators. Between each section on the answering divisionand each sect-ion on the distributing division run trunk-lines terminating in jacks at each end. The line-circuits are not connected to jacks at any board. They terminate in two plugs, connected in multiple, one plug at each division of boards. The plugs of the various lines are distributed among the sections on each division. For example, section 1 on the answering division contains the plugs of lines 1 to 200. Section 2 of the answering-board contains plugs of lines 201 to 400, and so on. This partition of lines by numbers is not necessary at the answering division. In like manner the first section on the distributing division contains plugs of lines 1 to 300 and section 2 contains plugs of lines 301 to 600, and so on. In this way the lines have plugs at both divisions of boards, each line having one plug at each division. Some partition of subscribers lines in groups at the distributing division is necessary, and the trunk-lines at the answeringsections are labeled so that the answering operator knows what group of subscribers lines are accessible over them. Trunk-lines running to section 1 on the distributing division may, for example, all be labeled 1-3, since they reach to lines 1300. Some trunklines labeled 1-3 are at each answeringsection, so any line at any answering-section may be connected to lines 1300. Section 2 of the distributing division has trunk-lines 3-6 from eachsection, so labeled at all sections. Any character or combination of characters may be used to designate trunk-lines as long as the operators can tell what substation-lines are accessible through them. Thus it appears that each answering-section has trunk-lines to each distributing-section labeled to indicate where they run. On the answering-section where a line has a plug the line is also provided with a calling device, such as an annunciator. These anuunciators are placed beyond the reach of the operators, if desired. These anuunciators act as both calling and clearing-out indicators. Each trunk-line has an indicator at the distributing division at the section to which it runs.

When a subscriber calls, the answering operator takes up the plug of his line at her board and inserts it into the trunk-line running to that section of the distributing divi-' sion where the called subscribers plug is located. The operator at that distributingsection places the plug of the called subscriber in the trunk-line jack at her board.

In the drawings, Figure l is a diagram view of the organization of switchboards, lines,

ferring to Fig. 2 for these connections more in detail, it will be seen how the subscribers lines are connected to the plug contact. Upon the plug A are mounted, on either side, two contacts, the two contacts on one side of the plug being connected in multiple to one of the line conductors. For example, line conductor a is connected in multiple to plugcontacts a and a. Line conductor a is connected in multiple to plug-contacts a and a The same is true of the contacts on plug A The connection between the plug-contacts and the line conductors is shown in connection with plug A The contacts a and a are connected to a flexible conductor (U, which is connected in tum to a long flexible spring within the tube a. Likewise contacts a and a are connected to a flexible conductor a and conducting-spring a in the tube a These tubes may be of insulating'material or they may be metallic and insulated from each other. The cords, springs, and tubes should be so proportioned and related that the spring never leaves the tube. All the plugs are connected to line-circuits in the same manner. The plugs rest normally in socket-bases a. The line conductor a is connected to a back contact (1 normally in contact with a spring a, which is connected with the calling-annunciator The other side of this callingannunciator is connected by wire a to the generator G, which is adynamo whose current is toned down by impedances and condensers in the manner well known to tele-.

phone-engineers. The annunciator a is provided with a flap a, adapted, when the coil is energized, to be attracted so as to display its number and to close a circuit with the contact a. The contact a is connected by wire a through the pair of contacts normally closed, a to ground at G. The contacts a are opened by the bend (0 which is operated by the ridge a on the plug A Whenever the plug is withdrawn from its base a or replaced upon its base a. tacts (1.13 a are at the distributing division of boards only and situated in the plug-seats at said division. The pairs of contacts (L are at the answering division of boards only.

The purpose of this organization is now evident. The subscriber A closes key-contacts G23, thereby closing the following circuit: ground at G, key-contacts C623, line-wire a, back contact a, spring-contact a, annunciator a battery-wire a, battery G, and ground at G. This circuit operates annunciator a, attracting its flap and closing the circuit through the contact a. WVhen the subscriber opens the key-contacts a the annnnciator-circuitis still complete through the contact (618, wire a, contacts a and ground at G. When the operator at the answering division of boards lifts the plug A the contacts (L are momentarily opened and the flap a of the annunciator leaves the contact (L and is restored to its normal condition without any manual work on the part of the operator. After the subscriber has closed the contacts 6& he removes his telephone from its hook and informs the operator at the central station with what subscriber he Wishes to talk. The operator at the central station is provided with a telephone set 0, terminating The pairs of con in contacts 0 and 0, adapted to make connection with the plug-contacts a and a", so that as these contacts are preferably on the tips of her fingers the act of taking up the plug connects her telephone set to the calling subscriber. After finding out the desired subscriber the operator places the plug A into a jack J, belonging to a trunk-line T, running to that section of the distributing-board where the called subscriber has a plug.

In Fig. 2 the called subscriber is represented by the line B. This line has plugs B and B The plug B is at the distributing division, where the trunk-line calls are distributed among the called subscribers, and the plug 13 is located at the answering division, where the callin g-subscribers wan ts are attended to.

In Fig. 1 is shown the normal condition of the trunk-lines. Trunk-line T, for example, comprises trunk-wires tand t, terminating in jacks J and J. At jack J at the answering division the wire t terminates in the insulated contact-spring The trunk-wire 2f terminates in contact-spring 15 which is normally connected to a stud t electrically connected to the switchboard S. The switchboard is grounded at G, as shown. At jack J at the distributing division the trunk-wires t and t terminate in insulated contact-springs t and To each trunk-line wire tis connected at the distributing division an indicator t the other side of which is connected to the battery-wire a The trunk-line indicators are normally on closed circuit, as follows: from ground at G, generator G, battery-wire a indicator t, trunk-conductor i, contact-spring i contactstud t normally connected thereto, and

ground at G.

WVhen a plug-is inserted into a jack J, the contact-sprin g t is lifted from the contactstud 29*, thereby opening the circuit of the indicator t and releasing its flap. This displays a signal to the operator at the distribu ting-board, informing her that her attention is desired at the trunk-line terminating in jack J. The operator at this board is provided with an operators telephone set 0, connected to a plug P. The plug P is constructed in the same manner as the plugs A A B B, except that the contacts a a b b are omitted. The contacts 19 of the plug P and the contacts a a b b are all so sunken below the plane of the surface of the plugs as not to come into contact with the metal of the switchboard when inserted into a jack. The contacts 19 on the plug P may, however, not be so sunken. The operator, upon seeing this signal displayed by the indicator t, inserts her plug P into the jack J, thereby connecting the plugs 13 and p to the jack contactsprings 25 and 25 respectively. The operator at the answering-board still maintains the contact between her thimbles 0 and 0 and the plug-contacts a and a and is thereby connected to the trunk-line with her telephone set. 1 She then informs the operator at IIO 7 the distributing-board, or permits the calling subscriber to inform the operator at the distributing-board, what line is desired. The operator at the distributing-board then withdraws her plug P and inserts it in the jack of another calling trunk-line, and at the same time with her thimble-contacts 0 and 0 conneeted to a calling-generator G lifts the plug B from its base 60 and inserts it into the jack J. The act of taking hold of the plug 13 connects the thimble-contacts 0 and 0 to the plug-contacts b and b so that the mere act of lifting the plug from its resting-place to the jack of the trunk-line sends outa calling-eurrent to the called subscriber. It is thus seen that the amount of work which can be done by an operator at the distributingboard depends upon the rapidity with which she can move her plug P from one trunk-line jack to another.

Referring to the details of the indicator i as shown in Fig. 2, it will be seen that the indicator is provided with a flap i, resting in the norm alposition shown in broken lines at i. The flap is pivoted at 1 and by means of a connecting-rod i is operated by an armature z". WVhen the armature is attracted, the flap '1) is in a vertical position. When the armature is released, the indicator assumes an oblique position. This oblique position indicates to the operator that her attention is desired. Upon the armature i is a catch 1 adapted by gravity to catch hold of the end of the plug inserted into the jack, so as to retain it against the force of an ejectingspring '6 The plug is provided with a slot 17, in which the catch 01 rests. When the indicator t is again energized, the armature i is attracted, the catch 2 leaves the slot 17, and the spring i ejects the'plug from the jack. This indicator i is energized when the circuit is again grounded for clearing out. In the same circuit is placed an additional plug-retaining magnet i at the answering division, normally attracting armature 1' but when a plug is inserted into the jack'J releasing the armature, so that its catch 1' will retain the plug in the jack against the force of the ejecting-spring i WVhen the circuit is energized upon clearing out, the plug is released and under the influence of the spring i it is thrown out of the jack. When the plugs at the two ends of the trunk-line are thus released, they fall back to their bases a without the assistance of the operator. This may be accomplished by weights and pulleys or by the springs a and a", as shown. These plugs and cords require more or less supervision by operators in returning to their seats. The value of this automatic disconnection lies largely in the release of trunklines for use by other subscribers. Many changes in circuits and details may be made.

When a subscriber has been called, as, for example, subscriber B in Fig. 2, his callingannunciator is cut off by the opening of contacts c4 and a, so that he is unable to call central, or so that when he clears out his annunciator will not indicate a call. These contacts are opened automatically by the withdrawal of the plug from its base. In

like manner it subscriber A had been called and his plug A had been switched for use the contacts a and a would have been opened and his annunciator would have been cut off from the line.

The generator G is preferably of the direct current type, and has in its circuit a tertiary coil of an induction-coil. The induction-coil belongs to the distributing-operators telephone set O', and the tertiary coil 0 is for the purpose of detecting a variation in the direct current from G There is preferably a separate generator G for each distributingboard operator, though with suitably arranged resistances and condensers this is not a necessity. The bells at the subscribers station which I use with this direct-current generator are a magnet-coil with a normallyopen short circuit around the coil closed by the passage of the current through the coil. In this way there is no break in the circuit, and the operation of the bellcreates a variation in the resistance of the circuit which is audible in the telephone set 0' at the central oflice of the calling operator. Upon hearing this buzz the distributing operator knows that the subscriber is free and connects his line to the trunk. If the called subscriber is busy, the call-bells are withdrawn from the circuit at the subscribers station and the resistance of the circuit is not rapidly Varied.

Hence the operator at central hears no buzz the trunk-line at the answering-board.

In the telephone outfit at the subscribers station the wire a leads to the receiver 1, secondary coil 2, and contact-point 8, adapted to make connection with the contactplate 7 on the hook 6 when the receiver is removed from the hook.

When the telephone-receiver is on its hook, the circuit is open at contacts 7 and 8. At this time the circuit is normally closed from wire a through wire 21, contact-plate 9, contact-point 10, bells 1 1, and thence to line-wire a. This circuit is opened when the telephone is removed from its hook.

The line conductors are insulated from the hook-lever. The lever is in a local-battery circuit with the battery 4, transmitter 5,-primary coil 3, and contact 23, closed when they is restored to its hook, the contact-plate 14,

connected to line-wire a,strikes this grounded lever 16 and grounds the line-circuit for re- IIO The plate 7 is connected by wire 22 'to the line conductor a.

storing purposes. It is obvious, however, that the contacts c0 may be closed manually by the subscriber in clearing out, if desired. I prefer, however, the automatic clearing-out signal.

WVhcn a subscriber hangs up his telephonereceiver, the momentary grounding of the line through the lever 16 operates the callingannunciator at central at the answeringboard, which thereupon attracts its flap, indicatin g that a disconnectionis desired. This operation of the flap adds another ground to the line through the contact (L18 and the pair of contacts a which is retained until the plug A is ejected from the jack, and the ridge (0 opens the contacts (L20 while passing back to its base ca The first grounding of the line by the subscriber may be enough to operate this ejector, and if so the second grounding of the line through the contact a is superfluous. The indicator i has also meanwhile released its plug, but if there has been a hitch here the grounding of the contactspring i through the stud '6 (see Fig. 1) will be sure to operate this coil to release the plug. If the plug still sticks to the jack, the indicator has, by its action on the flap 2', informed the distributing operator that a disconnection is desired. Thus safeguards upon safeguards are added to the operation of this system.

The great reduction in the amount of work on the part of the operators at the two divisions of boards enables one operator to do the work of a large number of subscribers, perhaps even two hundred and fifty. In fact, this is a conservative estimate.

In operation this system is quick. A subscriber closes the contacts a and takes his telephone off from its hook. The indicator at central indicates the call. The answering operator where the indicator is placed lifts the plug of the calling subscriber, and this act cuts in her telephone set and at the same time restores the calling-annunciator. Upon finding the number of the desired subscriber she inserts the plug already lifted into the jack of a trunk-line running to that part or section of the distributing-board where the called subscribers plug is located. The act of connecting to the trunk-line automatically causes the trunk-line signal at the distributing-board to indicate a want. The distributing operator inserts her telephone-set plug P and upon finding out the line wanted from either the operator or the subscriber (the latter saves time) lifts the plug of the called subscriber, and if she hears the buzz of the called-subscribers call-bell in her telephone she inserts the plug into the jack of the trunkline, simultaneously inserting the plug P into another calling trunk-line. To make a connection requires but one motion on the part of the answering board operator and two moves on the part of the connecting or distributing board operator. A total of three moves is required to make a connection, rendering a connectioneasicr with this divided switchboard than with the usual multiple switchboard. WVhen the subscribers are through with their conversation, they hang up their telephones, and this act causes the plugs to be automatically ejected from the trunk-jacks and restored to their bases. This disconnection is taken away from the operator, and after once establishing a connection she needs to pay no more attention to it.

The number of jacks on a switchboard in an exchange of ten thousand subscribers is greatly reduced. Instead of ten thousand jacks, as in the usual multiple board, there are from fifteen to forty-five on each answering-section and about fifty on a distributin g-section. This is on the ratio of about fifteen connections for every one hundred subscribers. This enormous saving in jacks is a big factor in the cost of putting in telephone-exchanges. Switchboards can be indefinitely extended after being planned for a certain number. That is, a switchboard built for one thousand may be extended to do the work of ten thousand by mere additions.

There are numerous alterations andsubstitutions that maybe made without departing from the spirit of my invention.

What I claim, and desire to secure Letters Patent for, i's I 1. In a telephone-exchange, the combination of an answering division, a distributing division, and line-circuits each connected to two plugs, one plug at each division.

2. In a telephone-exchange, the combination of an answering division, a distributing division, and line-circuits each connected to two plugs, one plug at each division, and circuit-con nectin g apparatus between said divisions.

3. In a telephone-exchange, the combination of an answering division, a distributing division, line-circuits, each connected to two plugs, one plug at each division, circuit-connecting apparatus between said divisions, and call-receiving devices at said answering division for said line-circuits.

4. In a telephone-exchange, the combination of an answering division, a distributing division, line-circuits each connected to two plugs, one plug at each division, and call generators or devices at said distributing division adapted to signal over said line-circuits.

5. In a telephone-exchange, the combination of an answering division, a distributing division, line-circuits, each connected to two plugs, one plug at each division, circuit-connecting apparatus between said divisions, and an operators telephone at said answering division adapted to be connected to said line-circuits.

6. In a telephone-exchange, in combination two divisions of boards, an answering division, and a distributing division, linecircuits each connected to a plug at one division and another switching device at the otherdivision, and circuit-connecting apparatus between said divisions.

said divisions for interconnecting said linecircuits.

S. In a telephone-exchange, the combination of an answering division, a distributing division, line-circuits each connected to a plug at the distributing division and to another switching device at the answering division, and circuit-connecting apparatus between said divisions.

9. In a telephone-exchange, the combina-I tion of an answering division, a distributing division, line-circuits, each connected to two plugs, one at each division interconnecting or trunk-line circuits between said divisions for interconnecting said line-circuits, and annunciatorsfor said line-circuits at said answerin g division.

10. In a telephone-exchange, the combination of an answeringdivision, a distributing vision for said line circuits, and interconnecting circuits or trunks between said di-' visions, terminating at each division in springjacks or plug-sockets, and a signaling device for each trunk at the distributing division.

11. In a telephone-exchange, the combination of an answering division, a distributing division, line-circuits each connected to a plug at each-division, trunk-line circuits between said divisions for interconnecting said linecircuits, and automatic'disconnectors at each division to disconnect trunk terminals and line-plugs at the Will of a subscriber.

- 12. In a telephone-exchange, the combination of an answering division, a distributing division,line-circuits each connected to a plug at each division, trunk-lines between said divisions for interconnecting said plugs terminating at each division in spring-jacks or jack for ejecting said plugs therefrom at the will of a subscriber.

13. In a telephone-exchange, in combination, an answering division, a distributing division, line-circuits each connected to a plug at said" answering division and to another switching device at the other division, a callre ceiving device for each line-circuit at'said answering division, and an automatic restoring device for said call device operated by the act of taking up the line-plug for use.

14. In a telephone-exchange, in combination, an answering division, a distributing division, line-circuits each connected to a plug at the distributing division and to another switching device at said answering division, call-receiving devices, one for each line-circuit at the answering division, and switching devices atsaid distributing division for rendering said call-receiving devices inoperative while the line-circuits are in use at the distributing division. g

15. In a telephone-exchange, in combination, an answering division, a distributing division,line-circuits each connected to a plug at said distributing division and to another switching device at said answering division, interconnecting circuits between said divisions, call-receiving devices at said answering division for said line-circuits, circuitchanging apparatus at said distributing division operated automatically by the act of taking up a plug for switching purposes to render said call apparatus irresponsive to a subscribers call.

16. In a telephone-exchange, in combination, an answering division, a distributing division, line-circuits each connected to a switching device at each division, trunk-circuits between said divisions, call-annunciators at said answering division for said linecircuits at said answering division, a substation-telephone and call set in each of said line-circuits, each set including a switch-1ever'in a local circuitinsulated from the mainline circuit, a transmitter and battery in said local circuit, and call and telephone apparatus in main-line branches connected to insulated contacts on said lever, said circuits being opened and closed by the switching movements of said lever, and call-sendingapparatus at the distributing division for operating said call apparatus at the substation set.

- 17. In a telephone-exchange, an answering division of boards divided into sections, a distributing division of boards also divided into sections, a different group of substation -lines connected to terminals at each distributingsection, the substation-lines at said distributing division being also connected to terminals, one for each line, at said answeringdivision, connecting-circuits between each section of one division and each section of the other division, calling apparatus at saiddistributin g division for signaling to substations, operators telephone sets at each section of each division adapted to be interconnected for orders, and plug-and-cord connectingapparatus for connecting said substation-lines with said connecting-circuits.

18. In a telephone-exchange, an answering division of boards divided into sections, a distributing division of boards also divided into sections, a different group of substation-lines connected toterminals at each distributingsection, the substation-lines at said distributing division being also connected to termi- .nals, one for each line, at said answering division, connecting circuits between each section of one division and each section of the other division, and automatic disconnecting and restoring apparatus for said terminals, operated from substations.

19. In a telephone-exchange, a substation including transmitter, receiver, and bells, a

I IO

switch for the transfer of circuits from tele-' phone to signaling apparatus, a line-circuit, a switch device at central for switching said line for use, a'call-annunciator at central for said line-circuit in circuit with an operating device at said substation, a retaining-circuit closed by the operation of said annunciator while indicating a call, and a circuit-breaker in said retaining-circuit under the control of an operator for opening said retaining-circuit for the purpose of restoring said indicator.

20. In a telephone-exchange, a substation including transmitter, receiver, and bells, a switch for the transfer of circuits from telephone to signaling apparatus, a line-circuit having a switching device at central, a callindicator at central for said line-circuit in circuit with an operating device at said substation, a retainingcircuit for said call-indicator closed automatically by the operation of said indicator, and a circuit-breaker in said retainingcircuit for opening said retainingcircuit by the act of switching said line-circuit for use at central.

21 In a metallic circuit telephoneexchange, an answering division divided into answering-sections, a distributing division divided into distributing-sections; metallic linefcircuits, each provided with two switching-terminals, one terminal at each division, the terminals at the answering division dis tributed among the answering-sections, and the terminals at the distributing division distributed among the "distributing-sections, local connecting-circuits or trunk-lines extending from each an swerin g-section to all the distributing-sections; whereby the number of sections in each division may be indefinitely nc ease 22. The combination in a divisional exchange, line-circuits having terminal devices at each division, a trunk conductor extending between two divisions, a signal located at one terminal of said trunk conductor, a cir- Qi ncluding said gnal a d a ect ic generator normally closed at the other terminal of the trunk conductor, and a circuitbr a e f a the t r erm na Op a a tomatically by the act of making connection thereat, so that said circuit is opened and remains open as long as said trunk is connected thereto.

23. In combination, a divisional exchange, line-circuits having terminal switching de-v vices at each division, a trunk conductor extending between two divisions, a signal located at one terminal of said trunk conductors, a circuit including said signal and a source of electric current normally closed at the other terminal of the trunk conductor,

and a circuit-breaker at the latter terminal operated automatically by the act of making connection thereat, so that said circuit is opened when said connection is made.

24. In combination, a divisional switchboard, a distributing division, an answering division, operators sections on each division, groups of metallic circuits, one group connected to switching-terminals on each section of the distributing-board, the two limbs of each metallic circuit connected to two metallic switching-contacts respectively at its section on the distributing division, switching-- terminals for said metallic circuits at said answering division, said terminals being partitioned among said answering-sections, each terminal comprising two metallic contacts connected to the two limbs of its metallic circuit respectively, and trunk lines between each answering-section and each distributingsection, whereby any line calling at an answering-section may by means of the proper trunk-line secure connection to the desired subscriber at some one section on the distributing division.

25. In a divisional exchange, a distributing division, an answering division, line-circuits connected to switching devices at both divisions, trunk-circuits extending between said divisions, and a combined busy-test and subscribers call at said distributing-board.

26. In a divisional exchange, a distributing division, an answering division, line-circuits each connected to a switching device at each division, trunk conductors extendingbetween said divisions for connecting a circuit at one division with a circuit at the other division, a common source of current at central, callreceiving devices, one for each line-circuit at the answering division, said call-receivin g devices adapted to be operated by said source of current at the will of a subscriber.

27. In a switchboard, a plug, a flexible twoconductor set of cords, extensible springs in circuit therewith and so connected thereto as to exert a pull on said plug, and one or more tubes insulated from each other, and adapted to act as a guide for said springs and cords.

28. In a switchboard, a metallic face, studs or posts integrally formed therewith, blocks of insulating material mounted on said posts, contact-springs mounted on said blocks and plugs adapted to pass through said switchboard to make contact with said springs, said plugs have sunken contact-pieces adapted to escape connection with said switchboard.

29. In combination a switchboard having a metallic body, a ground connection therefor, contact-sprin gs, one adapted to be grounded, said grounded contact-sprin g being normally connected to said metallic switchboard for its ground connection, and adapted to be disconnected from said switchboard upon the insertion of a plug.

MYRON FRANCIS HILL. Witnesses:

J AMES '1. LAW, LEWIS D. HILL.

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